1. Field of the Invention
The present invention relates to an assembly for tamping ballast supporting a track having two rails extending in a longitudinal direction which are fastened to a succession of ties, the tamping assembly comprising a vertically adjustable tamping tool carrier and a pair of tamping tools mounted on the carrier for reciprocation towards and away from one another in the longitudinal direction, each of the tamping tools being pivotal about a swivel axis extending in the direction of elongation of the ties and including at least one tamping pick arranged at the lower end of the tamping tool and intended for immersion in the ballast upon vertical adjustment of the tamping tool carrier, the tamping pick being mounted on the tamping tool for pivoting about a pivot axis extending perpendicularly to the swivel axis. A pivot drive designed as a hydraulic cylinder is connected to the tamping pick for pivoting the same in the direction of elongation of the ties, and squeezing drives are provided for reciprocating the tamping tools in the longitudinal direction.
2. Description of the Prior Art
U.S. Pat. No. 4,537,135 discloses a ballast tamping assembly designed especially for operation in switch areas of a track. Each tamping tool of this assembly comprises two tamping picks for immersion in the ballast which are arranged adjacent one another in the direction of elongation of the ties. A separate pivot drive is associated with each of said two tamping picks, thus providing a high degree of adaptability of the tamping picks which may be laterally pivoted out of the way to avoid colliding with various obstacles often present in switch areas. Depending on requirements, one or both tamping picks may be swivelled upwards into an inoperative position.
Another ballast tamping assembly is known from U.S. Pat. No. 5,269,226, likewise having two tamping picks per tamping tool which are arranged side-by-side in the longitudinal direction of the ties. The tamping pick closer to the rail of the track to be tamped is fixedly connected to the tamping tool, while the adjacent tamping pick may be pivoted by means of a pivot drive from a first to a second operating or end position. Both end positions are precisely delimited by respective stops. Thus, in a time-saving manner, the tamping tools need no longer be centered by the operator.